1. Field of the Invention
The present invention relates to the propagation, preparation for transport, transport, and delivery of live yeast, and in particular to the preparation and shipping of a container of concentrated yeast slurry or sediment, the container portioned off from a larger container in which the yeast was grown so as to protect the yeast from contamination by the external environment.
2. General Background and Description of Related Art
Mankind has practiced brewing since Neolithic times. Evidence of beer making has been found in the earliest writings of recorded history. Common to all brewing processes is the use of yeast and/or bacteria which multiply quickly and which ferment carbohydrates into alcohols and carbon dioxide. Yeast is essential in the production of beer, wine, spirits, and bread. Yeasts are amongst the simplest living organisms, and readily grow on moist surfaces and in liquids that are rich in nutrients.
During the standard brewing process, grain is first malted to help release the starches contained within the grain and to enzymatically convert those starches into fermentable sugars. Subsequently the malted grain is milled or cracked and then mashed to extract the sugars into a water solution called wort. During the mashing process the wort is boiled to remove excess water, to denature the starch-breaking enzymes, and to sterilize the wort. Optionally, the wort may then be boiled with hops, herbs, or additional sugars to impart flavor, color, and aroma. The wort is then cooled to a temperature at which yeast can be added, and the wort is inoculated with pure yeast. These yeast multiply quickly and ferment the sugars into alcohols and carbon dioxide. It is important that the yeast added to the wort is very pure, and that contamination is avoided because any unintended microorganisms entering the nutrient rich wort will easily multiply and impart undesirable flavors and/or disturb the brewing process. By the end of the fermentation period, the yeast settles to the bottom of the fermenter in a slurry or sediment layer.
There are myriad types of yeast used in brewing, and type of yeast selected influences the character and flavor of the final product. Regardless of the yeast chosen, or the mixture of yeasts chosen, adding yeast that is free from contamination is important due to the aforementioned consequences of contamination by unintended microorganisms. There is thus a need for pure yeast cultures.
Like the process of fermentation described above, the propagation of pure yeast is a delicate process requiring specific temperatures, air and nutrient supply, and a complete lack of contamination. Problems arise when batches of yeast prepared for sale or use are discarded because they are contaminated during the yeast-propagating process. Unlike the process of fermentation described above, where the finished product is the alcoholic byproduct of the years metabolism, the finished product in the present yeast culture preparation is the pure yeast itself, rather than the alcoholic byproduct of the yeast metabolism.
Thus, yeast production facilities strive to be extremely clean and to avoid contamination at all costs. Such production facilities have developed many means, techniques, and protocols to minimize the risk of contamination. It is beyond the scope of this disclosure to discuss all such past innovations, however, some of the prior art means, techniques, and protocols most relevant to the current application are described below.
It is known in the pharmaceutical industry to grow cultures in-situ in plastic bags or containers and then to ship the culture in those same containers. Because the bags or containers are never opened, this technique offers increased sterility and decreased opportunity for contamination. The downside to this technique is that bags of yeast propagated in this manner often contain only a small amount of concentrated yeast and a large amount of less valuable liquid. As brewers typically require large amounts of concentrated yeast, the shipment of huge quantities of less valuable liquids is wasteful at best, and at worst impracticable. There is currently no way to separate the concentrated and valuable yeast from the less valuable liquid taking up the majority of the volume of the container. Thus, there is a need to separate out the concentrated yeast whilst not subjecting the contents of the fermenter to contamination from the environment.
U.S. Pat. No. 3,946,780 discloses a simple plastic bag fermentation container with a one-way valve to allow fermentation gasses to pass out of the container while not allowing bacteria or other contaminants to enter. This bag does not include a means for concentrating the yeast grown therein and further does not completely isolate the yeast from the environment. Moreover, the '780 patent relates to the fermenting of yeast, where the desired product to be output from the system is alcohol in a medium. In processes such as the '780 patent, the sediment of yeast is often discarded while the liquid phase is sold or used in additional processes.
U.S. Pat. No. 4,063,383 discloses a sterile bag to which a user adds mushroom spores and growth medium. The user then seals the bag and lets the spores grow to a state at which the sealed bag may be sold and/or shipped to others who want to grow mushrooms. This bag allows transpiration and does not provide a means for concentrating the contents of the bag subsequent to the growth stage. The '383 patent fails to describe or teach a method of providing a concentrated amount of spores or yeast in a bag that does not allow growth during transport. Preventing further growth during transport is important when shipping a highly concentrated bag, because any growth therein could cause the bag to inflate or explode during shipping.
U.S. Pat. No. 4,708,938 discloses a method of making yeast through alcoholic fermentation within a closed system wherein externally applied pressure causes the fermented liquid to be expelled from a first bag and into a smaller bag. This system separates the yeast from the external environment but is needlessly complicated, increasing both the cost and risk of contamination. Further, this system is related to the separation of beer from the contaminated yeast.
Canadian Pat. No. 1228767 shows the use of heat-sealing to package baker's yeast. In this instance, yeast is placed in a package that is then completely sealed and thus rendered nearly impervious to oxygen, carbon dioxide, and water vapor. A small amount of carbon dioxide metabolizes out from the yeast, generating a protective cushion around the yeast in the bag. A method of separating a concentrated portion of the contents of the bag is not disclosed. Moreover, this device merely provides a container capable of absorbing a small amount of growth and gas generation. The publication does not describe a container that is aerated so as to induce large amounts of growth nor does it describe the portioning off of a smaller container of concentrated yeast. Finally, this patent concerns a dry yeast, and accordingly has a much longer shelf life and a lesser need for temperature regulation.
All of the above prior art suffers from one or more of the following limitations or deficiencies: the production or shipping of a concentrated liquid yeast culture in a section of a bag in which it was grown and separated out from while preventing contamination by the external environment, a mechanism that provides for vigorous aeration of the yeast in order to promote growth, and a way to separate out a concentrated quantity of yeast growth without risk of contamination.
It is thus a first object of the present invention to prepare and ship a container in which live liquid yeast is propagated and concentrated while being protected from external environment contamination.
It is a further object of the invention to decrease shipping costs by concentrating propagated liquid yeast in a bag that allows no venting or contamination during or prior to shipping.
It is a further object of the invention to decrease the difficulty and risk of contamination in propagating, handling, and shipping yeast.
It is a still further object of the invention to accurately assess the concentration of liquid yeast in a bag through noninvasive sampling of the yeast before shipping.
These and other objects, advantages, features and aspects of the present invention will become apparent as the following description proceeds. To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter more fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but several of the various ways in which the principles of the invention may be employed.